The present invention generally relates to a packaging system with heat sealing device for packaging articles with heat sealing film, and in particular to a sealing device capable to heat-seal leading and tailing ends of articles of different sizes.
Package films made of plastics or other heat sealable materials are widely used in packaging a variety of products, such as foods, compact disks for computer software and music and books, to protect the products from being damaged or contaminated. In a packaging process, a package film is placed around an article to be packaged. Edges of the package film are then heated to seal along sides of the article. Thus, an important factor that influences the productivity of a packaging line is the heat sealing operation performed by a packaging system.
A conventional packaging system forms an L-shaped sealing line along two adjacent sides of an article to be packaged. In other words, it seals two sides simultaneously. However, the operation of the packaging system is intermittent for the packaging device must be idle when articles to be packaged are being conveyed to the packaging system. The productivity is thus limited. Furthermore, articles to be packaged may have variable sizes and shapes. This causes deficiency in final package made by the conventional packaging system. For example, as shown in FIGS. 10 and 11, due to different thickness (dimension in a vertical direction) of the articles to be packaged, a sealing line A or Axe2x80x2 may no be located midway of the thickness of an article B. It may be below (sealing line A) or above (sealing line Axe2x80x2) the middle line. Such a situation causes certain problems. For example, the sealing line may not be properly formed or the package film be damaged or undesired over-packaging be caused. Eventually, the quality of the products is negatively affected.
It is desired to have a packaging system which can accommodate different sizes of articles to be packaged and providing a continuous packaging line for enhancing productivity thereof
Accordingly, an object of the present invention is to provide a packaging system comprising a device for sealing leading and tailing ends of articles of different thickness.
Another object of the present invention is to provide a packaging system comprising an end sealing device capable to move with respect to an article conveyor for continuously packaging articles carried by the conveyor and thus enhancing packaging efficiency.
A further object of the present invention is to provide a packaging machine comprising an end sealing device for forming a sealing line without causing damage to the package film.
A still further object of the present invention is to provide a packaging system capable to form sealing line without causing damage to the package itself and articles packaged thereby.
To achieve the above objects, in accordance with the present invention, there is provided a packaging system comprising a conveyor belt having a carrying surface for carrying an article to be packaged by a package film and an end sealing device including spaced upper and lower sealing blocks between which the article passes. A recessed chamber is formed in the carrying surface by extending the conveyor belt around specially arranged rollers. The end sealing device includes a machine frame slidably supported on rails. A driving system includes a motor and a reciprocating mechanism having an adjustable stroke coupling the machine frame to the motor. The rollers of the recessed chamber are attached to the machine frame to be movable therewith. The upper and lower sealing blocks are movably supported on the machine frame by upright posts with the lower sealing block accommodated in the chamber of the conveyor. Racks extend from the upper and lower sealing blocks with a toothed wheel matingly interposed therebetween for mechanically coupling the sealing blocks together. Driving devices, such as pneumatic cylinders, are provided to selectively drive the sealing blocks toward each other for performing sealing operation on the article. The racks are selectively disengageable from the toothed wheel to decouple the sealing blocks from each other thereby allowing adjustment of the distance between the sealing blocks for accommodating articles of different sizes.